Search
Use the search bar or filters below to find any TAPPI product or publication.
Filters
Content Type
Publications
Level of Knowledge
Committees
Collections
Journal articles
Magazine articles
Kraft recovery boiler operation with splash plate and/or beer can nozzles — a case study, TAPPI Journal Octobr 2021
ABSTRACT: In this work, we study a boiler experiencing upper furnace plugging and availability issues. To improve the situation and increase boiler availability, the liquor spray system was tuned/modified by testing different combinations of splash plate and beer can nozzles. While beer cans are typically used in smaller furnaces, in this work, we considered a furnace with a large floor area for the study. The tested cases included: 1) all splash plate nozzles (original operation), 2) all beer can nozzles, and 3) splash plate nozzles on front and back wall and beer cans nozzles on side walls. We found that operating according to Case 3 resulted in improved overall boiler operation as compared to the original condition of using splash plates only. Additionally, we carried out computational fluid dynamics (CFD) modeling of the three liquor spray cases to better understand the furnace behavior in detail for the tested cases. Model predictions show details of furnace combus-tion characteristics such as temperature, turbulence, gas flow pattern, carryover, and char bed behavior. Simulation using only the beer can nozzles resulted in a clear reduction of carryover. However, at the same time, the predicted lower furnace temperatures close to the char bed were in some locations very low, indicating unstable bed burning. Compared to the first two cases, the model predictions using a mixed setup of splash plate and beer can nozzles showed lower carryover, but without the excessive lowering of gas temperatures close to the char bed.
Journal articles
Magazine articles
Corrosion damage and in-service inspection of retractable sootblower lances in recovery boilers, TAPPI Journal October 2021
ABSTRACT: Several reports of accidents involving serious mechanical failures of sootblower lances in chemical recovery boilers are known in the pulp and paper industry. These accidents mainly consisted of detachment and ejection of the lance tip, or even of the entire lance, to the inside of the furnace, towards the opposite wall. At least one of these cases known to the author resulted in a smelt-water explosion in the boiler.In other events, appreciable damage or near-miss conditions have already been experienced. The risk of catastrophic consequences of the eventual detachment of the lance tip or the complete lance of a recovery boiler soot-blower has caught the attention of manufacturers, who have adjusted their quality procedures, but this risk also needs to be carefully considered by the technical staff at pulp mills and in industry committees.This paper briefly describes the failure mechanisms that prevailed in past accidents, while recommending inspection and quality control policies to be applied in order to prevent further occurrences of these dangerous and costly component failures. Digital radiography, in conjunction with other well known inspection techniques, appears to be an effective means to ensure the integrity of sootblower lances in chemical recovery boilers used in the pulp and paper industry.
Journal articles
Magazine articles
Displacement washing of softwood pulp cooked to various levels of residual lignin content, TAPPI Journal September 2021
ABSTRACT: This study investigates the influence of the degree of delignification of kraft spruce pulp cooked at seven different kappa numbers, ranging from 18.1 to 50.1, on the efficiency of displacement washing under laboratory conditions. Although the pulp bed is a polydispersive and heterogeneous system, the correlation dependence of the wash yield and bed efficiency on the Péclet number and the kappa number of the pulp showed that washing efficiency increased not only with an increasing Péclet number, but also with an increasing kappa number. The linear dependence between the mean residence time of the solute lignin in the bed and the space time, which reflects the residence time of the wash liquid in the pulp bed, was found for all levels of the kappa number. Washing also reduced the kappa number and the residual lignin content in the pulp fibers.
Journal articles
Early design-stage biorefinery process selection, TAPPI JOURNAL November 2012
Early design-stage biorefinery process selection, TAPPI JOURNAL November 2012
Journal articles
CFD-modeling for more precise operation of the kraft recovery boiler, TAPPI JOURNAL November 2012
CFD-modeling for more precise operation of the kraft recovery boiler, TAPPI JOURNAL November 2012
Journal articles
Southern pine oxygen delignified pulps produced in a Berty throughflow reactor: How to obtain the highest degree of delignification while maintaining pulp yield and quality, TAPPI JOURNAL March 2012
Southern pine oxygen delignified pulps produced in a Berty throughflow reactor: How to obtain the highest degree of delignification while maintaining pulp yield and quality, TAPPI JOURNAL March 2012
Journal articles
Stoichiometric model of chlorine dioxide delignification of softwood kraft pulps with oxidant-reinforced extraction, TAPPI JOURNAL March 2012
Stoichiometric model of chlorine dioxide delignification of softwood kraft pulps with oxidant-reinforced extraction, TAPPI JOURNAL March 2012
Journal articles
Bleaching of eucalyptus kraft pulps with chlorine dioxide: Factors affecting the efficiency of the final D stage, TAPPI JOURNAL March 2012
Bleaching of eucalyptus kraft pulps with chlorine dioxide: Factors affecting the efficiency of the final D stage, TAPPI JOURNAL March 2012
Journal articles
Assessment of pulp machine white water quality at market kraft pulp mills, TAPPI JOURNAL March 2012
Assessment of pulp machine white water quality at market kraft pulp mills, TAPPI JOURNAL March 2012
Journal articles
Effect of black liquor replacement in wheat straw soda-AQ cooking and lignin structure of pulps, TAPPI JOURNAL May 2012
Effect of black liquor replacement in wheat straw soda-AQ cooking and lignin structure of pulps, TAPPI JOURNAL May 2012